Exploring the Link Between Football Players and ALS: Rory Siegel, DO

Football has long been celebrated for its physicality, intensity, and enduring place in American sports culture. With the 2026 NFL season now underway, conversations surrounding the sport have evolved considerably over the past decade. Growing attention toward the long-term neurological effects of repeated head impacts has prompted researchers and clinicians to examine how participation in football may influence the risk of neurodegenerative disease, including amyotrophic lateral sclerosis (ALS).

Although ALS is a relatively rare and often sporadic neurodegenerative disease, emerging research has identified a potential association between football participation and increased ALS incidence. Researchers have begun examining factors including duration of football participation, exposure to repetitive head impacts, and differences across playing positions as they work to better understand what may contribute to neurological risk among players.

With the changing landscape of research, knowledge, and awareness surrounding America’s biggest sport, questions remain about what may drive the potential association between football participation and ALS and how clinicians should interpret the available evidence. In a recent conversation with NeurologyLive^®, Rory Siegel, DO, brain injury attending physician at Burke Rehabilitation Hospital, in White Plains, New York, discussed current research on length of football careers and ALS, the potential role of repetitive head impacts, and unanswered questions that could help clarify the relationship between the sport and long-term neurological health.

What does current evidence tell clinicians about ALS prevalence or risk among former or current football players?

Rory Siegel, DO: I know it has been very big in the media, especially with Chris Johnson recently coming forward with his ALS diagnosis. I do want to preface this by saying that a lot of the facts I will discuss are from a JAMA Neurology study that was published in 2021. This study covered football players from 1960 to, I believe, 2019, with a total of almost 20,000 players.

From this study, they found the incidence of ALS in football players to be four times higher than in the average person. Knowing that, and with some of the more recent public outcomes of ALS, it has definitely shocked the football-loving community and shown the potential risk of football and multiple head traumas. So, taking this into consideration, there is definitely a risk there. But I think there needs to be more research to really elucidate this fact.

What supporting evidence strengthens the association between football participation and ALS, and how convincing do you find that evidence?

That's probably the main study out there right now, at least speaking to the association between football and ALS. As we've covered before, there are other neurodegenerative diseases associated with football and other sequelae or repercussions of multiple head trauma that happens in football.

I think the claims are getting stronger and stronger. The fact that this study specifically had football players spanning decades really does show that there is a pattern. They were even able to look at age, race, and other components of the football players. They weren't really able to find any other associations except for the length of their career.

Looking at the roughly 60-year time span, the clearest association was career length. The players who developed ALS had NFL careers that were about 2.5 years longer, on average, than those who did not develop ALS. Overall, NFL players had nearly four times the incidence and mortality of ALS compared with the general US male population.

Are there other factors that may be associated with a higher incidence of ALS among football players beyond career length?

Right now, I think the association is mostly career length. I think we definitely have to look into the number of hits. The study was unable to show any correlation between positions played and the diagnosis or incidence of ALS.

From running back to lineman to kicker, there was no clear correlation. So, I think a more focused study on certain positions, the number of hits that players experience, or the amount of rest breaks they take at practice could highlight some more potential avenues of research.

It's encouraging that we have this information, but again, we do need some more specifics. I do hope that the science community can really work with the NFL to get those answers shortly.

How might repetitive head impacts, concussions, or the cumulative physical demands of football contribute to neurodegenerative disease, and specifically to the relationship with ALS?

There are many articles and studies about chronic traumatic encephalopathy, or CTE, which is a result of multiple head traumas. This is similar to earlier onset dementia, with changes to personality, which can be encountered after players have multiple head traumas. Unfortunately, that is a diagnosis that can only be given once the player has passed and an autopsy is performed.

But knowing that there's a four-times-increased risk of ALS, and that there have been other studies published showing an increased risk of Parkinson disease and other neurodegenerative diseases, definitely alludes strongly to the fact that multiple head traumas do cause neurological sequelae, pathology, or problems down the road.

Our brain is a center to everything. You can't continue to hit it without potentially allowing for a full recovery. Maybe that's something to look into, but that does lead to things down the road. The risk is there.

Again, the lines are becoming clearer as we move forward, but we definitely need to realize that the risk exists. As for what other factors we could potentially alter or modify, we still need more research to determine that.

Given that more research is needed in this relatively new space, how should clinicians interpret the current evidence? Is there enough information to suggest that a history of playing football should be considered when evaluating someone's risk of developing ALS?

The risk of developing ALS is interesting because 90% to 95% of cases are sporadic, meaning there is no identifiable cause. Whether it's something in the environment, who knows? It's not necessarily genetic, and that's the majority of cases. So, to strictly say that football causes ALS, we still can't quite say that. The risk is there, as with anything, and that's why we have to really prioritize brain health.

If anything were to happen during a practice or game, I think assessing the patient or player and making sure they're clear on all levels before returning is paramount to mitigating any potential second-impact syndrome or repeated head trauma to a brain that may already be in a fragile state.

What are some of the biggest unanswered questions about the relationship between football participation and ALS?

I think we need to delve a little bit further into whether certain positions in football or the quantity of head impacts are associated with ALS. I think that's probably the most paramount question as of now.

The study investigated the length of a career, but, of course, all football players in this study are male. So how does this contribute to potentially the female gender? I believe females are at about a 20% lower risk of ALS, or have a lower incidence of ALS, compared with males.

We don't necessarily have a professional women's football league that we could test, or that has, as we know, as wide of a 60-year time frame to assess. But that is certainly something to look into.

When we think about football, we think about the head impact over and over and over, and obviously the neurological sequelae that could result. So again, focusing on position, focusing on career length, potentially delving into the position and maybe even gender down the road with other studies could be some interesting questions to answer.

Is there anything else you would like to emphasize regraridng the potential relationship between football and ALS?

I would really like to stress again: We need to protect the brain. Studies have shown that these repetitive head traumas can cause neurodegenerative diseases. The number is small, but the risk is present and definitely more significant and tangible to those who play football compared to those who do not.

While we love this game as a country, myself included, there are real dangers, and we need to protect the brain. Whether that's having a more thorough assessment on the sideline should anything go wrong, potentially modifying the game's rules or protocols around head injuries, or changing the future of the sport to reflect the importance of brain health, who knows? But again, the brain is so paramount to everything we do. If we don't take the right steps to protect it, unfortunately, ALS could be a consequence.

Transcript edited for clarity.

REFERENCES
1. Daneshvar DH, Mez J, Alosco ML, et al. Incidence of and Mortality From Amyotrophic Lateral Sclerosis in National Football League Athletes. JAMA Netw Open. 2021;4(12):e2138801. doi:10.1001/jamanetworkopen.2021.38801